I'm experiencing the exact same thing but I believe the scores are pretty accurate given that I don't really remember the answer to questions, I just generally remember the gist of the question. Either way, like Earlcat said, you should be testing for overall improvement so just use these as practice and try to have a few tests set aside that you haven't taken yet if you want a more accurate indication of where you're scoring.

I've been doing the same thing after carelessly burning through most of the PrepTests without reviewing my wrong answers in detail. When doing the retakes, I force myself to finish much earlier (~30-31 mins per section) and I force myself to read all of the answer choices even if I think I've found the correct answer. My retake scores have been very high, but I've also noticed an improvement in "new" PrepTest scores, which are still not quite as high as my retake scores. What I've been doing is retaking old tests during the week, and taking 1-2 new test during the weekend (I have the out of print prep tests and 60, 61, 62 left). I think the important thing is to just remember that the scores on your retakes are not going to be representative.